1. Field of the Invention
The present invention concerns methods and devices for chilled distribution and heating of foods, in particular foods disposed on meal trays originating from institutional kitchens in which they are prepared.
2. Description of the Prior Art
Devices for the distribution and packaging of meals produced by institutional kitchens are already known in themselves, in particular the device described in document FR 2 442 035 A, in which the foods are prepared in an institutional kitchen where they are placed on trays having a first part for foods intended to be eaten hot and a separate second part for foods intended to be eaten cold. The trays are placed on a special manually propelled thermally insulated institutional cart which has a slotted vertical wall for separating and insulating the cold areas of the trays relative to the hot areas of the trays and which can be coupled to a fixed station for blowing hot or cold air. By coupling the cart to this station, pre-prepared meals can be kept chilled and the portion intended to be eaten hot can be heated before the trays are distributed.
In document FR 2 383 637 A corresponding to U.S. Pat. No. 4,020,310, U.S. Pat. No. 4,110,587 and DE 27 11 088 A, the foods to be heated are placed on the trays on plastics material plates the top face of which is covered with a thin aluminum dish and which receive a removable insulative cover the inside face of which is covered with a metal film. Some ten trays are supported in a thermally insulated institutional cart, one below the other and with an appropriate distance between them, and a series of induction shelves attached to a fixed station to which the cart can be coupled are inserted between the successive trays in the tray heating area. High-frequency alternating current is passed through the induction coils to generate a high-frequency alternating magnetic field that heats by magnetic induction the aluminum dish covering the plate and the metallic bottom face of the cover.
These prior art institutional distribution devices using an institutional thermally insulated cart and a fixed station have a number of drawbacks. Firstly, all the trays on the same cart are heated simultaneously, so that they must necessarily be distributed simultaneously, with no possibility of varying meal times to suit different persons. Next, the distribution of the trays necessitates the intervention of personnel who must therefore be available at meal times, with no possibility of shifting the working times of personnel relative to meal times. Also, the carts necessarily have a complex structure, thermally insulated relative to the exterior and with additional thermal insulation between the parts of the trays to remain cold and the parts of the trays carrying the foods to be heated. The device is therefore costly to manufacture and to use. Also, at meal times, the personnel has to distribute the trays to a number of persons. The usual distribution conditions make this a relatively lengthy process and necessitate transporting foods exposed to the air, with the result that hygiene conditions are not generally respected.
The same drawbacks are found in the device described in document FR 2 349 112 A in which two carts each carrying some twenty meal trays are introduced into a refrigerated enclosure. Electrical elements embedded in each tray heat the food intended to be eaten hot. Heating of the tray by the electrical elements that it contains inevitably causes unacceptable heating of the food intended to be eaten cold.
Document FR 2 604 882 A discloses an individual unit for storing and heating meals for distribution ahead of meal times in institutions. This device is an individual closed enclosure delimited by a thermally insulative peripheral wall and provided with an access door. Its interior space is divided into a plurality of small compartments insulated from each other by fixed insulative walls, at least two compartments being cooled by a refrigerator unit, one of the two cooled compartments being adapted to be heated by a heater. With a device of this kind, personnel can distribute meals ahead of meal times and meal times can be chosen individually for each person. However, hot and cold foods cannot be packaged on the same meal tray inside the device. At meal distribution time, the personnel must introduce the foods to remain cold and the foods to be heated separately into the respective compartments. This makes distribution more complex and entails the risk of errors being made. Moreover, at meal times, the person eating the meal must take out the hot foods and the cold foods separately, possibly to place them on a tray. These operations entail the risk of burns through contact with the hot plates and require sufficient capability and agility of the person eating the meal, which limits the applications of the device, in particular in the distribution of meals in hospitals.
The problem addressed by the present invention is that of designing a new method and a new device structure for storing, distributing and packaging meals from institutional kitchens enabling storage of meals previously prepared on trays having a first part for food intended to be eaten hot and possibly a separate second part for food intended to be eaten cold, enabling uninterrupted refrigeration during distribution of meal trays from the institutional kitchen to the persons eating the meals. Following distribution of meal trays, which can take place ahead of meal times, all the foods must be kept cool at an appropriate storage temperature, after which the foods intended to be eaten hot must be heated without requiring any other operation immediately prior to the individual meal time, the foods intended to be eaten cold remaining at an appropriate cool temperature. The person eating the meal must be able to obtain their meal tray without any additional action on the part of the distribution personnel.
To comply with hygiene requirements, it is important to prevent the growth of bacteria on the foods. The problem is to assure hygienic conditions whilst providing the persons eating meals with hot food at a temperature around 65.degree. C. throughout the food and cold food at a temperature around 8.degree. C. throughout the food.
Another problem addressed by the present invention is that of reducing the cost of the equipment required for institutional distribution of meals, in particular by avoiding the use of costly special-purpose carts, and facilitating the use of the equipment by providing a specific method avoiding difficult manipulation of foods during distribution and eating of meals, freeing up the distribution personnel from time constraints and enabling persons lacking in agility to obtain their meals themselves.